This issue of Phil. Trans. R. Soc. A is the second part of a double issue devoted to the virtual physiological human (VPH) initiative, which has been launched as part of the European Commission's Seventh Framework Programme for Research and Development.

Historically, organ-specific ‘vertical’ modelling has largely developed based on independent efforts dedicated to the various organ systems, and it is one of the aims of the VPH to (re-)unite these efforts for mutual benefit. The potential of this can be illustrated even by this small collection of papers. The reasons for wanting to do so are that (i) many of the ‘horizontal’ level-of-integration-specific challenges are common among biological tissues and (ii) the VPH ultimately needs to be able to ‘couple’ the different organ systems (what is a heart without blood flow, what is blood pressure regulation without the kidney, what oxygen carrier is blood in the absence of lungs and what is brain function without oxygenation?).

Of course, this represents only a snapshot of the vast range of research questions that are already being targeted by VPH-related efforts. The diverse activities call for integration, from topical access solutions to existing knowledge and models (Harris et al. 2009), to cross-community collaboration, integration and exchange (e.g. via network activities as described in http://www.vph-noe.eu).

Still, the VPH initiative is on a path-finding mission. We are therefore delighted that the Royal Society has allowed us to communicate part of this work via its Phil. Trans. R. Soc. A. We are looking forward to providing further updates via this longest running scientific journal, which—belying its age—has been firmly at the forefront of attention to, and support of, the post-genomic challenges of developing a quantitative biology of systems such as the VPH.

Acknowledgments

Compilation of this issue was supported by the European Commission FP7 ‘Virtual Physiological Human Network of Excellence’ grant (project 223920) and the FP6 ‘normaCOR’ grant (project 018676). The editors are indebted to Naomi Jordan and Katherine Fletcher for their expert management of the compilation of this issue.

Footnotes

One contribution of 15 to a Theme Issue ‘The virtual physiological human: tools and applications II’.